General recruiting has slowed down now so I think you'll be safe. If the instructors are paid by student instead of a wage, they'll fight to keep you.
I'd sit down with the CFI and an instructor you like and hammer out a plan. Sure, weather can wreck the best plans but you're the customer so tell them what you'd like. See if you can book this instructor in advance over several weekends/week days etc.
You are right though, you shouldn't have too many changes during your initial phases of training.
Later on (eg line training) it doesn't matter so much.
